Brief post on the marriages in Massachusetts and a legal question

Posted in good part to garner regyt's opinion, but anyone who knows is welcome to tell me.

Alright, so the Gov. of Mass. is trying to limit the availability of homosexual marriage to Massachusetts residents or those intending to live in Mass.

The basis of this is an old (1912?) Mass. law that limits granting marriage licenses to any couple who isn't local or doesn't intend to be local. I'm not sure about the specifics of what happens when the couple doesn't live in the same state, but I don't think that's important for this particular case.

Now a law that hasn't been enforced for some time can be enforced without warning or selectively. See 'jaywalking.'

So, what I'm wondering is does selective enforcement of this law against homosexuals only violate equal protection under the law? In analogy, African Americans have sued about traffic laws that are enforced only against them. This would actually be an easier case as a whole because the law is being explicitly used against homosexual marriage.

Now, if this law is enforced against heterosexuals as well, there'd be no basis for this particular argument. But if it isn't, is there a solid case?